Photographic sensitizing dyes of the merocyanine and styryl types in silver halide photographic emulsions



United States 3,397,981 PHOTOGRAPHIC SENSITIZING DYES OF THE MEROCYANINEAND STYRYL TYPES IN SIL- VER HALIDE PHOTOGRAPHIC EMULSIONS Lewis L.Lincoln and Leslie G. S. Brooker, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporationof New Jersey No Drawing. Continuation-impart of application Ser. No.226,756, Sept. 27, 1962. This application Mar. 7, 1966, Ser. No. 532,100

7 Claims. (Cl. 96102) ABSTRACT OF THE DISCLOSURE Merocyanine and styryldyes derived from 1,2-alky1ene benzimidazoles and 1,2-alkylenenaphthimidazoles are valuable spectral sensitizers for hydrophiliccolloid silver halide emulsions used in coating light-sensitive layersand photographic elements.

This application is a continuing application of Lincoln and Brooker,U.S. Ser. No. 226,756, filed Sept. 27, 1962, now abandoned.

This invention relates to photographic sensitizing dyes, and moreparticularly, to merocyanine type and styryl dyes derived from1,2-alkylene imidazole bases and their syntheses.

Certain merocyanine and certain styryl dyes useful in increasing thesensitivity of photographic silver halide emulsions have been known. Newclasses of these dyes have been desired.

One object of our invention is to provide novel merocyanine and styryldyes having a bridged structure that are valuable for use inphotography.

Another object is to provide merocyanine and styryl dyes which extendthe sensitivity of photographic silver halide emulsions into longerwavelength regions of the spectrum.

Another object is to provide a method for making our bridged merocyanineand bridged styryl dyes.

Still another object of our invention is to provide photographic silverhalide emulsions sensitized with our dyes.

Still further objects will become evident from the followingspecification and claims.

According to our invention, we provide new merocyanine type dyesincluding those represented by the formula:

I RI RI! R!!! wherein Z represents the nonmetallic atoms necessary tocomplete a heterocyclic ring, such as those of the benzimidazole series,e.g.,

benzimidazole, 4-chlorobenzimidazole, 5-chl0r0benzimidazole,6-chlorobenzimidazo1e, 7-chlorobenzirnidazole, 4-methyl benzimidazole,S-methylbenzimidazole, 6-methylbenzimidazole, S-bromobenzimidazole, 6bromobenzimidazole, 4phenylbenzimidazole, S-phenylbenzimidazole, 4-methoxybenzimidazole,

3,397,981 Patented Aug. 20, 1968 S-methoxybenzimidazole,6-methoxybenzimidazole, S-iodobenzimidazole, 6-idodobenzimidazole,4-ethoxybenzimidazole, S-ethoxyflbenzimidazole, tetrahydrobenzimidazole,5,6-dimethoxybenzimidazole, S-hydroxybenzimidazole,6-hydroxybenzimidazole, etc.,

those of the naphthimidazole series, e.g.,

naphth[2,3-d]imidazole, 4-chloronaphth [2,3-d1imidazole,5-chloronaphth[2,3-d]imidazole, 6-bromonaphth[2,3-d]imidazole,7-iodonaphth [2,3-d] imidazole, 8-chloronaphth[2,3-d1imidazole,S-methylnaphth[2,3-d1imidazole, 6-methoxynaphth[2,3-d]imidazole,6-methylnaphth[2,3-d1imidazole, 7-methoxynaphth[2,3-d]imidazole,7-ethylnaphth[2,3-d]imidazole, etc., e.g.,

naphth[2,l-d]imidazole, 5-chloronaphth[1,2-d1imidazole, 6-bromonapht-h[1,2-d] imidazole, 6-iodonaphth[1,2-d]imidazole, 7-methylnaphth[ 1,2-d]imidazole, 6-methoxynaphth[ 1,2-d] imidazole,5-ethoxynaphth[1,2-d]imidazole, etc., and

naphth[1,2-d]imidazole, 4-chloronaphth[2, 1 -d]imidazole,5-chloronaphth[2, l -d]imidazole, 6-iodonaphth[2,l-d]imidazole,7-bromonaphth[2,1-d]imidazole, 4-methylnaphth[2,l-d]imidazo1e,S-methoxynaphth[2,l-d]imidazole, 6-ethylnaphth [2, l-d] imidazole,5-hydr0Xynaphth[2,1-d]irnidazole, etc., etc.;

R represents an alkyl group, such as methyl, ethyl, npropyl, isopropyl,n butyl, isobutyl, n-amyl, n-octyl, fi-hydroxyethyl, fi-chloroethyl,B-acetoxy, S-sulfoethyl, sulfopropyl, sulfobutyl, carboxymethyl,carboxyethyl, carboxypropyl, carboxybutyl, etc.; n is the integer 1 or2; m is the integer 1 or 2; and Q represents the nonmetallic atomsnecessary to complete an acidic ketomethylene heterocyclic nucleuscontaining from 5 to 6 atoms in the heterocyclic ring, includingheterocyclic rings such as those of the rhodanine series (e.g.,rhodanine, 3-methylrhodanine, 3 ethylrhodanine, 3-phenylrhodanine,3-ocnaphthylrhodanine, etc.), those of the pyrazolone series (e.g.,3-methyl 1 phenyl-S-py-razolone, l-phenyl-S-pyrazolone,l-(2-benzothiazolyl)-3-methyl 5 pyrazolone, etc.), those of theisoxazolone series (e.g., 3phenyl- 5(4H)isoxazolone, 3methyl-5(4H)isoxazolone, etc.), those of the oxindole series (e.g.,1-alkyl-2,3-dihydro-2- pxindoles, etc.), those of the2,4,6-triketohexahydr0- pyrimidine series (e.g., .barbituric acidseries) and the 4,6 diketo-2-thiohexahydropyrimidine series (e.g., 2-thiobarbituric acid series), as well as their l-alkyl (e.g., l-methyl,l-ethyl, l-n-propyl, l-n-heptyl, etc.) or 1,3-dialkyl (e.g.,1,3-dimethyl, 1,3-diethyl, 1,3-di-n-pr0pyl, 1,3- diisopropyl, 1,3dicyclohexyl, 1,3-di(Bmet-hoxyethyl), etc.), or 1,3-diaryl (e.g.,1,3-di-phenyl, l,3-di(p-chloro phenyl), 1,3-di(p-ethoxycarbonylphenyl,etc.) or l-aryl (e.g., l-phenyl, l-p-chlorophenyl, etc.) orl-alkyl-3-aryl (e.g., 1-ethyl-3-phenyl, 1-n-heptyl-3-pheny1, etc.)derivatives, those of the 2(3H)imidazo[1,2-a]pyridone series,

those of the 5,7 dioxo-6,7-dihydro--thiazolo[3,2-a1pyr imid'ine series(e.g., 5,7 dioxo-3-phenyl-6,7-dihydro-5- thiazolo[3,2 a]pyrimidine,etc.), those of the Z-thio- 2,4(3H,5H) oxazoledione series, (e.g.,3-ethyl-2-thio- 2,4-oxazolidinedione, etc.), those of thethianaphthenone series (e.g., 3(2-H)-thianaphthenone, etc.), those ofthe 2 thio-2,5-thiazolidinedione series (i.e., the 2-thio-2,5-(3H,4H)thiazoledione series) (e.g., 3 ethyl-2-thio-2,5-thiazolidinedioue, etc), those of the 2,4-thiazolidinedione series(e.g., 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3phenyl-2,4-thiazolidinedione, 3-a-naphthyl-2,4- thiazolidinedione,etc.), those of the thiazolidinone series (e.g., 4-thiazolidinone,3-ethyl-4-thiazolidinone, 3phenyl 4-thiazolidinone,3-ot-naphthyl-ethiazolidinone, etc.), those of the 4-thiazolinone series(e.g., 2-ethylmercapto- 4-thiazolinone,2-alkylphenylamino-4-thiazolinones, 2-diphenylamino-4-thiazolinone,etc.), those of the Z-amino- 2,4-oxazolinone (i.e., pseudohydantoin)series, those of the 2,4-imidazolinedioue (hydantoin) series (e.g., 2,4-imidazolinedione, 3-ethyl-2,4-imidazolinedione, 3-phenyl- 2,4imidazolinedione, 3 a-naphthyl-2,4-imid-azolinedione, 1,3 diethyl2,4-imidazolinedione, 1-ethyl-3-anaphthyl 2,4 imidazolinedione,1,3-diphenyl-2,4-imidazolinedione, etc.), those of the2-thio-2,4-imidazolinedione (i.e., 2 thiohydantoin) series (e.g.,2-thio-2,4- imidazolinedione, 3 ethyl-2-thio-2,4-imidazolinedione, 3phenyl 2-thio 2,4-imidazolinedione, B-u-naphthyI-Z- thio 2,4irnidazolinedione, l,3-diethyl-2-thio-2,4-imidazolinedione, 1 ethyl3-phenyl-2-thio-2,4-imidazolinedione, 1 ethyl3-a-naphthyl-Z-thio-Z,4-imidazolinedione,1,3-diphenyl-2-thio-2,4-imidazolinedione, etc), those of S-imidazolinoneseries (e.g., Z-n-propylmercapto-5-imidazolinone, etc.), etc., as wellas heterocyclic nuclei containing a sulfone group, such as thosedescribed in U.S. Patent 2,748,114, (e.g., 4 thiazolidone 1,1 dioxide,3(2H)-thianaphthenone-1,l-dioxide, etc.) (especially a heterocyclicnucleus containing 5 atoms in the heterocyclic ring, 3 of said atomsbeing carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of saidatoms being selected from the group consisting of a nitrogen atom, anoxygen atom, and a sulfur atom; R, R", and R each represents thehydrogen atom, a lower alkyl group, such as methyl, ethyl, propyl,butyl, etc., or an aryl group, such as p'henyl; R and R each representthe hydrogen atom, an alkyl group, such as methyl, ethyl, etc., and anaryl group, such as phenyl, such that when m is 2, R is hydrogen; andnew styryl dyes including those represented by the formula:

a cycloammonium quaternary salt represented by the formula:

III H n 1 wherein Z, R, R, R", R", X and n are as defined previously,with a compound having the formula:

wherein R R Q and m are as defined previously. The condensation canadvantageously be carried out in the presenceof a basic condensingagent, e.g., the organic tertiary amines, such as triethylamine,tri-n-propylamine, triisopropylamine, tri-n-butylamine, etc.,N-methyl-piperidine, N ethylpiperidine, N,N-dimethylaniline,N-N-diethylaniline, etc. The condensations can advantageously beeffected in the presence of an inert solvent, e.g., ethanol, n-propanol,isopropanol, 1,4 diox-ane, pyridine, quinoline, etc. Heating acceleratesthe condensations, and temperatures varying from room temperature to thereflux temperature of the solvent in the reaction mixture are used.

Our styryl dyes are made to advantage by the reactions of our inventionin which the cyclam'monium quaternary salt having the Formula III iscondensed with an aldehyde having the formula:

wherein R R and m are as defined previously. This condensation isadvantageously effected in the presence of a basic condensing agent,such as piperidine, and in the presence of an inert solvent, e.g.,ethanol, propanol, 1,4-dioxane, pyridine, quionoline, etc. Heatingaccelerates the reaction which is conveniently carried out between roomtemperature and the reflux temperature of the solvent in the reactionmixture.

The intermediates represented by Formula III are prepared advantageouslyby the reaction of a 1,2-diaminobenzene, a 1,2 diaminonaphthalcne or a2,3-diaminonaphthalene compound with a lactone such as a'y-butyrolactone, (e.g. 'ybutyrolactone, B-methyl-w-butyrolactone- 8ethyl 'y-butyrolactone, ,B-propyl-v butyrolactone, [3- butyl-butyrolactone, fi-phenyl-v-butyrolactone, fiq-dimethyl 'ybutyrolactone, mcthyl-y-butyrolactone, 'yethyl 'y butyrolactone,'y-propyl-y-butyrolactone, fiphenyl-y-methyl-vbutyrolactone, etc.) or ae-valerolactone (e.g., 6 valerolactone, fl-methyl-fi-valerolactone, ,8ethyl 6 valerolactone, ,B propyl-6-valerolactone, 7 methylfi-valerolactone, 'y-ethyl-a-valerolactone, 6- methyl-fi-valerolactone,e-ethyl-fi-valerolactone, e-propyl- 6 valerolactone, 5phenyl-a-valerolactone, -phenyl-8- valenolactone, fiyydimethyl-fi-valerolactone, fi,'y,6-trimethyl-e-valerolactone, etc.). Thediaminabenzene or diaminonaphthalene compound used is provided with theappropriate substituents so they will be present on the base formed.Alternatively these substituents can be substituted on the base afterits formation. The cyclization reaction can be effected by heating thediamino-benzene or the diaminonaphthalene land lactone at atmosphericpressure or at an elevated pressure in an autoclave. In the presence ofsuitable solvents, such as diphenyl ether, or chlorobenzene the reactioncan be effected at lower temperatures. The base is then converted to thequaternary salt by heating with the appropriate alkylating agent.

In a preferred reaction, the intermediate of Formula III can be prepareddirectly without first forming the base. In this reaction the1,2-diaminobenzene, 1,2-diaminonaphthalene, or 2,3-diaminonaphthalenehas an alkyl group on one of the amino groups. The alkyl group may bemethyl, ethyl, propyl, butyl, etc. One of these (benzene or naphthalene)derivatives is then condensed with the appropriate lactone by heating inthe presence of an acid, such as phosphoryl chloride, a mixture ofhydrobromic acid and acetic acid, etc. in a suitable solvent, such asdimethylacetamide. The chloride salt of the quaternary ammonium compoundformed in the presence of phosphoryl chloride can be converted to thesalts having other anions by conventional means.

The following representative examples will illustrate more fully themanner whereby we practice our invention.

DYE 1 3-ethyl-5-[ (4-ethyl-1,2-dihydro-4H-pyrrolo[ 1,2-a] naphth[2,3-d1imidazolyl) -methylene] rhodanine H C-C z O C-NEt 3 ethyl 1,2trimethylenenaphth[2,3-d]imidazolium iodide (1 mol., 1.82 g.) and5-acetanilidomethylene-3- ethyl rhodanine (1 mol., 1.63 g.) were mixedin dry pyridine ml.) and heated to reflux temperature, triethylamine (2mols., 1.4 ml.) added and the mixture refluxed for thirty minutes. Themixture was then chilled, crystalline dye filtered off, washed withmethyl alcohol and dried. After two recrystallizations from pyridine theyield of pure dye was 0.15 g. (11%) M.P. 308-309 C.

DYE 2 3-ethyl-5- [4-ethyl-1,2-dihydro-4H-pyrrolo 1,2-a] naphth[ 1,2-d]imidazolyl) methylene] rhodanine H1CCH= I I 9 N C CH=C CS i/ \C// DYE 33-ethyl-5-[(4-ethyl-1,2-dihydro-4H-pyrrolo[1,2-a]

benzimidazolyl methylene] rhodanine H10 CH2 OC-NEt 3 ethyl 1,2trimethylenebenzimidazolium p toluenesulfonate (1 mol., 3.58 g.),S-acetanilidomethylene- 3-ethylrhodanine (1 mol., 3.56 g.) andtriethylamine (2 mols., 2.8 ml.) were dissolved in dry pyridine (30 ml.)and heated under reflux for ten minutes. The reaction mixture was thenchilled, crystalline dye filtered off,

washed with methyl alcohol and dried. After two recrystallizations frompyridine and methyl alcohol the yield of pure dye was 1 g. (25%) M.P.277278 C. dec.

DYE 4 3-ethyl-5 (5 -ethyl-4 (5H) piperidino[ 1,2-a] naphth [2,3-d]imidazolyl) methylene] rhodanine 3 ethyl 1,2 tetramethylenenaphth[2,3d]imidazolium-p-toluenesulfonate (1 mol., 2.1 g.),S-acetanilidomethylene-3-ethyl rhodanine (1 mol., 1.6 g.) andtriethylamine were dissolved in dry pyridine (20 ml.) and heated underreflux for thirty minutes. The reaction mixture was then chilled andcrude dye precipitated from solution by pouring into water withstirring. The solid dye was filtered off, washed with methyl alcohol anddried. After two recrystallizations from methyl alcohol the yield ofpure dye was 0.7 g. (33%) M.P. 259260 C. dec.

DYE 5 5-[ (6,7 -dichloro-4-ethyl- 1 ,2-dihydro-4H-pyrrolo[ 1,2-a]benzimidazol-3-yl) methylene] -3 -ethylrhodanine 5,6 dichloro-3-ethyl1,2 trimethylenebenzimidazolium iodide (1 mol., 1.9 g.) andS-acetanilidomethylene- 3-ethylrhodanine (1 mol., 1.5 g.) were mixed indry pyridine (25 ml.) and heated to reflux temperature, triethylamine (2mols., 1.4 ml.) added and the entire mixture refluxed for fifteenminutes. The mixture was then chilled and the dye obtained crystallineby adding an excess of methyl alcohol with stirring. The dye was thenfiltered off, washed with methyl alcohol and dried. After tworecrystallizations from pyridine and methyl alcohol the yield of puredye was 0.4 g. (20%), M.P. 311-612 C. dec.

DYE 6 5 [6,7 dichloro 4 ethyl 1,2 dihydro 4H pyrrolo[1,2 aJbenzimidazol3 yl)methylene] 1- ethyl-2-thiobarbituric acid 5,6dichloro-3-ethyl-l,Z-trimethylenebenzimidazolium iodide (1 mol., 1.9 g.)and 5-anilinomethylene-l-ethyl- 2-thiobarbituric acid (1 mol., 1.37 g.)which had been heated to a melt with acetic anhydride (4 mols., 1.88ml.), were mixed in dry pyridine (35 ml.) and heated to refluxtemperature, triethylamine (2 mols., 1.4 m1.) added and the entiremixture refluxed for fifteen minutes. The mixture was then chilled andthe dye obtained crystalline by adding an excess of methyl alcohol withstirring, crys talline dye filtered off, washed with methyl alcohol anddried. After two recrystallizations from pyridine and methyl alcohol theyield of pure dye was 0.4 g. (20%), M.P. above 320 C.

7 DYE 7 3 ethyl 5 [(4-ethyl-1-methyl-2,l-dihydro-4H-naphtho [2,3 d]pyrrolo[l,2 a]imidazol-3-yl)methylene]rhodanine DYE 8 3 pdimethylaminobenzylidene 4 ethyl-2,3-dihydro- 1H pyrrolo[l,2a]naphth[2,3-d]imidazolium-p-toluenesulfonate CNEt 3 ethyl 1,2trimethylenenaphth[2,3-d]imidazoliump-toluenesulfonate (1 mol., 2.04 g.)and p-dimethylaminobenzaldehyde (1 mol. plus 100% excess, 1.49 g.) weremixed in absolute ethyl alcohol (15 ml.), piperidine (1 drop) added andthe mixture refluxed for two hours.

The mixture was then chilled, crystalline dye filtered off, washed withacetone and dried. After two recrystallizations from methyl alcohol theyield of pure dye was 0.55 g. (20%) M.P. 298 -299 C. dec.

3 ethyl 1,2 trimethylenebenzimidazolium-p-toluenesulfonate (1 mol., 3.58g.) and p-dimethylaminohenzaldehyde (1 mol. plus 100% excess, 2.98 g.)were mixed in absolute ethyl alcohol (30 ml.), piperidine (3 drops)added and the mixture heated under reflux for 2 hours.

The mixture was then chilled, crystalline dye filtered off, washed withacetone and dried. After two recrystallizations from methyl alcohol theyield of pure dye was 0.7 g. (15%) M.P. 250251 C. dec.

8 DYE 10 6,7-dichloro-3-p-dimethylaminobenzylidene-4-ethyl-2,3-dihydro-1H-pyrrolo[ l,2-a]benzimidazolil1m iodide 5,6dichloro-3-ethyl-1,Z-trimethylenebenzimidazolium iodide (1 mol., 1.9 g.)and p-dimethylaminobenzaldehyde (1 mol. plus excess, 1.5 g.) were mixedin absolute ethyl alcohol (30 ml.), piperidine (4 drops) added and themixture refluxed for thirty-five minutes. The mixture was then chilled,crystalline dye filtered off, washed with acetone and dried. After tworecrystallizations from methyl alcohol the yield of pure dye was 0.5 g.(20%), M.P. 316317 C. dec.

DYE 11 3 p dimethylaminobenzylidene 4 ethyl-l-methyl-2,3- dihydro 1Hnaphtho[2,3 d]pyrrolo[1,2 a]imidazolium iodide4-ethyl-l-methyl-2,3-dihydro 1H naphtho[2,3-d]pyrr0lo[1,2-a]imidazoliumiodide (1 mol., 1.89 g.) and pdimethylaminobenzaldehyde (1 mol. plus100% excess, 1.49 g.) were mixed in absolute ethyl alcohol (50 ml.),piperidine (5 drops) added and the entire mixture refluxed for thirtyminutes. The mixture was then chilled, crystalline dye filtered 01f,washed with acetone and dried. After two recrystallizations from methylalcohol the yield of pure dye was 0.9 g. (36%), M.P. 320-321 C. dec.

Other merocyanine type dyes of our invention represented by Formula Iare made by methods similar to those illustrated by Dyes 1 through 7.For example dyes such as the following:

3-ethyl-5- (4-ethyl-1,2-dihydro-4H-pyrrolo 1,2-a]naphth[2,3-d]imidazolyl)allylidine1rhodanine 3-ethyl-5-(4-ethyl-1,2-dihydro-4H-pyrrolo[ 1,2-a] naphth I 1,2-d] imidazolyl)allylidene1rhodanine 3 -ethyl-5-[ (4-ethyl-1,2-dihydro-4H-pyrrolo[1,2-a]

benzimidazolyl allylidene] rhodanine 3ethy1-5-[(5-ethyl-4(5H)piperidino[1,2-a]naphth[2,3-d]

imidazolyl) allylidene1rh0danine Similarly other merocyanine dyes inwhich the rhodanine and barbituric acid nuclei are replaced by otherketomethylene heterocyclic nuclei are made according to our invention.

Other styryl dyes represented by Formula II are made according to ourinvention by methods similar to those illustrated by Dyes 8 through 11.

The preparation of the cyclammonium quaternary salts represented byFormula III is illustrated by the following typical examples.

9 3-ethy1-1,3-trimethylenenaphth[ 1,2-d]imidazolium-ptoluene sulfonateThis intermediate was prepared as follows: 1,2-diaminonaphthalene (1mol., 31.6 g.) and 'y-butyrolactone (1 mol., 17.2 g.) were mixed andheated at 270290 C. for seven hours at which time water (7 ml.) had beencollected. The remaining mixture which was a glassy mass was distilledunder reduced pressure (B.P. 145- 165 C. at 1.5 mm.). The product wasdistilled over as a yellow mass and was obtained solid by stirring withan excess of ether. At this point the solid was filtered 01f, stirredwith acetone, filtered off again, washed with a small amount of acetoneand dried. The yield of yellow solid1,2-trimethylenenaphth[1,2-d]imidazole was g. (36%) M.P. 121122 C.

' One mol., 10.4 g. of 1,2-trimethylenenaphth[1,2-d]- imidazole andethyl-p-toluenesulfonate (1 mol. plus 10% excess) were mixed and heatedat 115 C. for thirty-six hours. The mixture was then cooled and theglassy mass obtained as a pale pink solid by refluxing with an excess ofacetone. The product was then filtered off, washed with acetone anddried. The yield of crude pink solid was g. (98%) M.P. 18l-182 C. dec.

3-ethyl-1,2-tetramethylenenaphth[2,3-d1imidazoliump-toluenesulfonate1,2-tetramethylenenaphth[2,3-d]imidazole (1 mol., 9 g.) made by reacting2,3diaminonaphthalene with fi-valerolactone as described by Mosby,Journal of Organic Chemistry, vol. 24, page 419, March 1959, andethyl-ptoluene-sulfonate (1 mol. plus 10% excess 11 g.) were mixed andheated at 120 for three hours. The product as a hard cake was thencooled, ground under acetone, filtered off, washed with acetone anddried. The yield of light tan solid was 16 g. (94%) M.P. 201-202 C. dec.

3-ethyl-1,2-trimethylenebenzimidazolium-p-toluenesulfonate3-ethyl-1,2-trimethylenenaphth[2,3-d]imidazolium-ptoluenesulfonate1,2-trimethylenenaphth[2,3 -d]imidazole (1 mol., 12 g.) made by heating2,3-diaminonaphthalene with 'y-blltyrolactone, andethyl-p-toluenesulfonate (1 mol. plus 10% excess, 12.7 g.) were mixedand heated on a steam bath for twenty-four hours. The product as aviscous mass was then cooled, washed with ether, the ether decanted andthe salt obtained solid by stirring with an excess of acetone and dried.After two recrystallizations from ethyl alcohol the yield of pure saltwas 11 g. (44%) M.P. 172173 C.

Anhydro-3- 3-sulfobutyl) 1,2-trimethylenenaphth- [2,3-d]imizadoliumhydroxide 1,2-trimethylenenaphth[2,3-d]imidazole (1 mol., 20.8 g.) and2,4-butene sultone (1 mol., 13.6 g.) were mixed, heated at 130 C. forone hour, then heated at 110 C. for thirty-six hours and this product asa tan cake was ground under acetone. The salt was then filtered ofi,washed with acetone and dried. The yield of crude product was 32.5 g.(96%) M.P. above 310 C.

5,6-dichloro-3-ethyl-1,2-trimethylenebenzimidazolium iodide4,5-dichloro-N-ethyl-Z-aminoaniline (1 mol., 41 g.) and 'y-butyrolactone(1 mol., 17.2 g.) were mixed, phosphoryl chloride (1 mol., 18.3 ml.)added and much heat was evolved. After several minutes, the evolution ofheat subsided and the purple viscous mixture heated at refluxtemperatures for fifteen minutes. At this point, the dark brown mixturewas cooled, dissolved in refluxing methyl alcohol (450 ml.) and the saltconverted to the iodide by adding solid sodium iodide (2 mols., 9.2 g.)to the dark methyl alcohol solution with stirring. The iodide saltprecipitated from solution as a gray solid. After chilling the mixturethe gray solid was filtered off, washed with methyl alcohol and dried.The yield of product was 33 g. (43%) M.P. 282-283 C. dec.

1-methyl-2,3-dihydro-1H-naphtho[2,3-d]pyrrolo- 1,2-a] imidazole2,3-diaminonaphthalene (1 mol., 31.6 g.) and 'y-methylbutyrolactone weremixed in chlorobenzene (20 ml.) and the mixture heated under refluxdistilling 011 the chlorobenzene along with water as it was formed. Whenall of the chlorobenzene was distilled off (20 ml.) more ofchlorobenzene was added and the mixture again heated under refluxdistilling off the chlorobenzene with more water. After (6.4 ml.) ofWater had been collected the remaining chlorobenzene was removed and theresidual mixture distilled under reduced pressure (B.P. C. at 2 mm.).The yield of product as a yellow oil was 8 g. (18%).

4-ethyl-1-rnethyl-2,3-dihydro-1H-naphtho[2,3-d]pyrrolo[1,2-a]imidazoliumiodide l-methyl 2,3 dihydro 1H naphtho[2,3-d]pyrrolo- [1,2-a]imidazole(1 mol., 8 g.) and iodoethane (1 mol. plus 200% excess, 16.8 g.) weremixed and heated on a steam bath in the dark for twenty hours. Themixture was then cooled, stirred with an excess of ether, ether decantedand the product obtained as a white solid by stirring with an excess ofacetone. The solid was then filtered off, washed with acetone and dried.The yield of white solid was 11 g. (81%) -M.-P. 276-277 C. dec.

Any of our intermediates can be solubilized with other groups, such ascarboxyalkyl, acetoxyalkyl, etc., by reacting the base of theintermediate with the appropriate reactant. For example, a carboxymethylgroup can be added by reacting the base of the intermediate witha-bromoethylacetate, or a carboxyethyl group can be added by reactingthe base with B-bromopropionic acid. An acetoxyethyl group can be addedby reacting the base with fi-bromoethanol followed by acetic anhydride.

Our dyes are useful in spectrally sensitizing photographic silver halideincluding silver halide emulsions when incorporated therein. The dyesare especially useful for extending the spectral sensitivity of thecustomarily employed silver chloride, silver chlorobromide, silverbromide, silver bromoiodide and silver chlorobromiodide developing outemulsions using a hydrophilic colloid carrier such as gelatin, itswater-soluble derivatives, polyvinyl alcohol, its water-solublederivatives and copolymers, water-soluble vinyl polymers such aspolyacrylamide, imidized polyacrylamide, etc., and other water-solublefilm-forming materials that form water-permeable coatings, such ascolloidal albumin, Water-soluble cellulose derivatives like ethanolamine cellulose acetate, etc. To prepare emulsions sensitized with oneor more of our new dyes, it is only necessary to disperse the dye ordyes in the emulsions. The methods of incorporating dyes in emulsionsare simple and well known to those skilled in the art. In practice, itis convenient to add the dyes to the emulsion in the form of .a solutionin a suitable solvent. Methanol, ethanol, propanol, etc., acetone andpyridine are used to advantage. The dyes are advantageously incorporatedin the finished, washed emulsions and should be uniformly distributedthroughout the emulsions.

The concentration of the dyes in the emulsions can vary widely and willdepend upon the type of emulsion and the effect desired. The suitableand most economical concentration for any given emulsion will beapparent to those skilled in the art, upon making the ordinary tests andobservations customarily used in the art of emulsion making.

To prepare a hydrophilic colloid-silver halide emulsion sensitized withone or more of our new dyes, the following procedure is satisfactory. Aquantity of dye is dissolved in a suitable solvent such as an alcohol,acetone, pyridine, etc. and a volume of this solution, which may bediluted with water, containing the dye, is slowly added to about 1000cc. of gelatino-silver halide emulsion, with stirring. Stirring iscontinued until the dye is uniformly dispersed in the emulsion.

The above statements are only illustnative, as it will be apparent thatthe dyes can be incorporated in photographic emulsions by any of theother methods customarily employed in the art, e.g., by bathing a plateor film upon which an emulsion is coated in a solution of the dye in anappropriate solvent. However, bathing methods are ordinarily not to bepreferred. Emulsions-sensitized with the dyes can be coated on suitablesupports, such as glass, cellulose derivative film, resin film or paperin the usual manner.

Photographic silver halide emulsions, such as those listed above,containing the sensitizing dyes of my invention can also contain suchaddenda as chemical sensitizers (e.g., sulfur sensitizers, such as allylthiocarbamide, thicurea, allylisot'hiocyanate, cystine, etc.), variousgold compounds, such as potassium chloroaurate, auric trichloride, etc.(see U.S. Patents 2,540,085; 2,597,856; and 2,597,915, for example),various palladium compounds (such as palladium chloride (U.S.2,540,086), potassium chloropalladate (U.S. 2,598,079), etc.), ormixtures of such sensitizers), antifoggants (e.g., =benzotriazole,nitrobenzimidazole, S-nitroindazole, etc. (see Mees, The Theory of thePhotographic Process, Macmillan Pub., p. 460), or mixtures thereof),hardeners (e.g., formaldehyde (U.S. 1,763,533), chrome alum (U.S.1,763,533), :glyoxal (Ger. 538,713), dibromacrolein (Br. 406,750),etc.), color couplers (e.g., such as those described in U.S. Patent2,423,730, Spence and Carroll U.S. application 771,380, filed Aug. 29,1947, now U.S. Patent 2,640,- 776, issued June 2, 1953, etc.), ormixtures of such addena. Dispersing agents for color couplers, such 'assubstantially water-insoluble, high boiling crystalloidal materials,such as those set forth in U.S. Patents 2,322,027 and 2,304,940, canalso be employed in the above-described emulsions.

The following example will serve to further illustrate how our dyes areused to sensitize photographic emul- SlOIlS.

EXAMPLE 1 G. p-Methylaminophenol sulfate 2.0 Sodium sulfite, desiccated90.0 Hydroquinone 8.0 Sodium carbonate-H O 52.5 Potassium bromide 5.0

Water to make 1 liter.

fixed in a conventional sodium thiosulfate fixing bath, washed anddried. The following table summarizes the wavelength of light to whichthe maximum sensitivity was produced and the longest wavelength light towhich each emulsion was sensitized.

TABLE 1 Dye Silver halide Sensitivity Dye Sensi- Number in EmulsionMaximum, tizes to my light of my 1 Silver broruoiodide 570 620 1 Notdefinite.

Similarly it can be shown that other dyes of our invention can be usedto advantage to sensitize silver halide emulsions.

The immediate l,2-alkylenebenzimidaz'ole and 1,2-a1-kylenenaphthimidazole nuclei are not equivalent to the related1,2-alkylenebenzoxazoles, 1,2-alkylenenaphthoxazoles,l,2-alkylenebenzothiazoles, and 1,2-alkylenenaphthothiazoles ofcopending Lincoln and Heseltine, U.S. Ser. No. 226,757, filed Sept. 27,1962. The following example will serve to illustrate the saidnonequivalence.

EXAMPLE 2 A gelatino-silver bromoiodide emulsion was divided into fiveportions and each of the said portions was treated with a sensitizingamount of one of the carbocyanine dyes identified as Dyes A, B, C, D andE. A separate coating was made for each of the five sensitized emulsionson separate pieces of a photographic film support. When dried, theseemulsion coatings were each exposed to a wedge spectograph and givenphotographic processing using a hydroquinone type of developer, washed,fixed in a conventional sodium thiosulfate fixing bath, washed anddried. The wavelength of light producing the maximum sensitization wasdetermined from the processed wedge spectogram for each emulsioncoating.

The light absorption hin methanol was determined for each of the Dyes Athrough E.

The [following table lists the light absorption 7\- in methanol, thesensitization maximum and the difference between light wavelengthsproducing sensitization max and k- Light Absorption Sensitizationmaximum (my) Dye k-rnax in Methanol (mg) The following describes theDyes A through E by their structural formulae.

Dye Structural formula 14 We claim: 1. A light-sensitive layercontaining silver halide and a sensitizing dye selected from dyes havingthe formula:

0 I R! R R!!! Er n-(EH -(3H 0 C=CCH=CC l N R4 R6 r Q a I? Z 0CC(=OH-C)ml=O-'C=O oo-- c o-( I -N H3 H3 H1 H2 H2 H3 1 0 s wherein Zrepresents the nonmetallic atoms necessary to D complete a heterocyclicnucleus selected from the class consisting of a benzimidazole nucleus,and a naphthimid- N azole nucleus; n represents an integer of from 1 to2; m 6 represents an integer from 1 to 2; R represents an alkyl 5 2group having from 1 to 8 carbon atoms; R, R", and R' S S each representsa member selected from the class consisting of the hydrogen atom, analkyl group having from E o=cCH=CH-C 1 to 4 carbon atoms and a phenylgroup; R and R each represents a member selected from the classconsisting of I L the hydrogen atom, an alkyl group having-from 1 to 4 CC2115 1 carbon atoms, and a phenyl group, such that when m is 2 1 2, Ris hydrogen; and Q represents the nonmetallic atoms necessary tocomplete an acidic ketomethylene heterocyclic nucleus containing from 5to 6 atoms in the nucleus; and the dyes having the formula:

II R! II!!! R!!! Dye A containing the 1,2-trimethylenenaphthimidazoleH"+( CH)P1"J3H nucleus of the immediate application demonstrates aggre-,N i R, gation as evidenced by the 80 m difference between the lightwavelength producing sensitization maximum and the absorption A- Dyes B,C, D, and E, which do not have a l,2-alkylenenaphthimidazole or1,2-alkylenebenz- X R im dazole nucleus of the application, do notaggregate as wherein Z R, n and m are as defined; X represents anevidenced by a difierence 111 the wavelength producing acid radical, Rand R each represents a member selected sensitization maximum andabsorption kthat is, from f th 1 f th h d 1k 1 about 47about 69% lowerthan the difference for Dye tom c-ass y rotgen A. It is readily apparentfrom these comparative data that group avmg mm 0 car on a Oms an a p anythe immediate l,Z-trimethylenenaphthimidazole nucleus is not equivalentto either the nuclei of Lincoln and Heseltine, U.S. Ser. No. 226,757,that is, 1,2-trimethylenebenzothiazole, and1,2-tetramethylenenaphthoxazole, or the prior art benzoxazole nucleus.

The dyes A through B were prepared by condensing the appropriateintermediates dissolved in organic solvent by heating in the presence ofa basic condensing agent such as triethylamine. Dye A was prepared bycondensing 3- ethyl 1,2 tetramethylenenaphth[2,3 d]imidazoliumptoluenesul-fonate described previously herein, with 2-5-acetanilidovinyl 3 ethylbenzothiazolium iodide. Dye B was prepared bycondensing 2,3-trimethylenebenzothiazolium bromide made as described incopending Lincoln and Heseltine, U.S. Ser. No. 226,757, filed Sept. 27,1962 with Z-B-acetanilidovinyl 3 ethylbenzoxazolium iodide. Dye C wasprepared by heating a solution of 2,3-tetramethylenenaphth[2,3-d]oxazolium iodide, prepared as described in US. Ser. No. 226,757, andethyl ortho formate. Dye D is well known in the art. Dye -E was preparedby the method described for Dye B but substitutingZ-B-acetanilidovinyl-3-ethylbenzothiazolium iodide in place of 2 8-acetanilido-3-ethyl-benzoxazoliurn iodide.

The merocyanine and styryl dyes of our invention derived from1,2-alkylene benzimidazoles and 1,2-alkylenenaphthimidazoles arevaluable sensitizers for use in hydrophilic colloid silver halideemulsions used in photography. These dyes extend the sensitivity ofphotographic silver halide emulsions containing them into longerwavelengths.

The invention has been described in considerable detail with particularreference to preferred embodiments thereof, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention as described hereinabove and as defined in theappended claims.

group; and R, R and R are as defined previously.

2. A light-sensitive layer of claim 1 containing a sensitizing dyeselected from dyes having the formula:

wherein Z represents the nonmetallic atoms necessary to complete aheterocyclic nucleus selected from the class consisting of abenzimidazole nucleus, and a naphthimidazole nucleus; n represents aninteger of from 1 to 2; m represents an integer from 1 to 2; Rrepresents an alkyl group having from 1 to 8 carbon atoms; R, R", and R"each represents a member selected from the class consist ing of thehydrogen atom, an alkyl group having from 1 to 4 carbon atoms and aphenyl group; R and R each represents a member selected from the classconsisting of the hydrogen atom, an alkyl group having from 1 to 4carbon atoms, and a phenyl group, such that when m is 2, R is hydrogen;and Q represents the nonmetallic atoms necessary to complete aheterocyclic nucleus containing from 5 to 6 atoms in the nucleusselected from the class consisting of a rhodanine nucleus, a pyrazolonenucleus, an isoxazolone nucleus, an oxindole nucleus, a2,4,6-triketohexahydropyrimidine nucleus, a 4,6-diketo 2thiohexahydropyrimidine nucleus, a 2(3H) imidazo[l,2-a] pyridonenucleus, a 5,7-dioxo-6,7-dihydro 5 thiazolo [3,2-a]pyrimidine nucleus,at 2-thio-2,4-(3H,5H)oXazoledione nucleus, a thianaphthenone nucleus, a2-thio-2,5- thiazolidinedione nucleus, a 2,4-thiazolidinedione nucleus,a thiazolidinone nucleus, a 4-thiazolinone nucleus, a 2- 15 imino 2,4-oxazolinone nucleus, 21 2,4-imidazolinedione nucleus, a2-thio-2,4-imidazolinedione nucleus, and a 5- imidazolinone nucleus; andthe dyes having the formula:

group; and R, R and R are as defined previously.

3. A light-sensitive layer of claim 1 containing 3-ethylimidazolylmethylene1rhodanine.

4. A light-sensitive layer of claim 1 containing 3-ethyl- 5-[(5 ethyl4(5H) piperidino[1,2-a]naphth[2,3-d]imidazolyl)methylenehhodanine. 5. Alight-sensitive layer of claim 1 containing 3-ethyl-5-[(4-ethy1-1-rnethyl 1,2 dihydro 4H naphtho[2,3-d] pyrrolofl,2-a]imidazol-3-yl methylenekhodanine.

6. A light-sensitive layer of claim 1 containing3-pdimethylaminobenzylidene 4 ethy12,3-dihydro-1H-pyrrolo[1,2-a]naphth[2,3-d]imidazolium-p-toluenesulfonate.

7. A light-sensitive layer of claim 1 containing3-pdimethylaminobenzylidene-4-ethyl 1methyl-2,3-dihydro-1H-naphtho[2,3-d]pyrrolo[l,2-a]imidazolium iodide.

References Cited UNITED STATES PATENTS 9/1960 Nys et a1. 96106 3/1966Liber et al. 96l05 OTHER REFERENCES J. TRAVIS BROWN, Primary Examiner.

